1. Technical Field
The present invention relates to rotating electric machines which have a coil formed by arranging each corresponding pair of end portions of electric conductors to adjoin each other and welding them at end surfaces thereof, and to methods of manufacturing the rotating electric machines.
2. Description of Related Art
There are known rotating electric machines which have a coil formed by arranging each corresponding pair of end portions of electric conductors to adjoin each other and welding them at end surfaces thereof.
For example, Japanese Patent No. JP3303854B2 discloses an automotive alternator which has a stator coil formed by welding a plurality of substantially U-shaped conductor segments to one another. More specifically, each of end portions of the conductor segments has a cut (or notch) formed therein. Each corresponding pair of the end portions of the conductor segments are arranged to have parts thereof where no cut is formed adjoin each other, and then welded at end surfaces thereof. Consequently, with the cuts formed in the end portions of the conductor segments, it is possible to weld each corresponding pair of the end portions of the conductor segments with a reduced heat input to the pair of the end portions during the welding.
On the other hand, however, due to the cuts, it may become easy for the molten metal mixture to sag outside the pair of the end portions of the conductor segments during the welding. Consequently, it may become difficult for the molten metal mixture to form a uniform weld bead shape. As a result, the strength of a weld formed between the pair of the end portions of the conductor segments may become uneven and thus local stress concentration may occur in the weld.